Optical grain evaluation device and combine harvester provided with optical grain evaluation device

An optical grain evaluation device comprising:

• a light source;
• a light-projecting part through which light from the light source is projected to stored grain;
• a light-receiving part on which light that has been projected to the grain through the light-projecting part and transmitted through the grain is incident, the light-receiving part being lined up with the light-projecting part at a distance;
• a grain evaluation unit configured to evaluate the grain based on information relating to the light received by the light-receiving part;
• a shielding part that separates an area between the light source and the light-projecting part from an area between the light-receiving part and the grain evaluation unit, so as to prevent light from the light-projecting part from directly entering the light-receiving part;
• and
• a shutter that is provided separate from the shielding part so as to be switchable between an open state in which the light from the light source is allowed to pass through the light-projecting part, and a closed state in which the light is prevented from passing through the light-projecting part,
• wherein the area between the light source and the light-projecting part, and the area between the light-receiving part and the grain evaluation unit are configured, over the entirety of the areas, as air transmission areas in which light is transmitted through air.